Most babies don't consistently sleep through the night until around 9–10 months. At 3 months, 44.5% of babies in our dataset slept through — but that drops back to 32.4% at 4 months and crashes to 23.6% at 6 months before steadily climbing. By 12 months, 87.5% of nights are wake-free.
The journey is not linear. There are three clear disruption points — at 4, 6, and sometimes 9 months — that most parents experience as a confusing step backwards. Understanding why each one happens, and what's driving your baby's specific pattern, is what actually moves the needle.
This is what 1,816 complete sleep logs from 176 real babies actually show.
About this data
- ·1,816 complete sleep-day logs from 176 babies tracked in the Cocoo app
- ·Only complete days were included — days where the app could verify full 24-hour coverage without significant tracking gaps
- ·Ages 0–14 months; groups with fewer than 5 logs excluded
- ·All data is aggregate and anonymized — no individual baby's data is identifiable
- ·“Sleeping through the night” = zero recorded night wakings for that calendar night
The full picture by month
What a complete sleep log actually looks like at each age — percentages sleeping through, median night sleep hours, average night wakings, and average nap count.
| Age | Sleep through* | Night sleep (median) | Avg wakes/night | Avg naps/day |
|---|---|---|---|---|
| 0 mo | 16.1% | 9.78h | 1.81 | 3.2 |
| 1 mo | 9.4% | 9.47h | 1.99 | 3.4 |
| 2 mo | 16.8% | 9.33h | 1.68 | 3.6 |
| 3 mo | 44.5% | 11.05h | 0.99 | 3.3 |
| 4 moregression | 32.4% | 10.19h | 1.16 | 3.4 |
| 5 mo | 42.8% | 10.54h | 1.04 | 2.8 |
| 6 moregression | 23.6% | 10.13h | 1.4 | 2.6 |
| 7 mo | 47.1% | 10.7h | 0.89 | 2.3 |
| 8 mo | 46.3% | 10.58h | 0.85 | 1.9 |
| 9 mo | 60.4% | 10.65h | 0.86 | 1.9 |
| 10 mo | 68.2% | 10.83h | 0.56 | 1.9 |
| 11 mo | 67.9% | 10.97h | 0.54 | 2 |
| 12 mo | 87.5% | 10.96h | 0.21 | 1.5 |
| * “Sleep through” = zero recorded night wakings. Pink rows = known regression months. | ||||
Finding 1: The path is not linear — there are three disruption points
The most striking pattern in the data is that “sleep through” rates don't climb steadily. They spike, then drop, then spike, then drop again:
Parents who read generic milestones (“most babies sleep through by 3–4 months”) are blindsided by the 6-month crash, which hits harder than the 4-month regression in our data. It's the single biggest disruption point for families who thought they were through the hard part.
Finding 2: Night wakes peak at 1 month, not at birth
Counterintuitively, our data shows the most frequent night wakings happen not at birth, but at 1 month — averaging 1.99 wakings per night. Newborns (0 months) average 1.81 wakings, and the number then starts to fall through 3 months (0.99).
Average night wakings by age
But notice the bumps: wakings tick back up at 4 months (1.16) and again at 6 months (1.40). These are the same two regression points visible in the sleep-through percentages. They're not coincidental — they're the same developmental events showing up in two different metrics.
The practical question isn't whether waking is normal (it clearly is) — it's whether the wake is driven by hunger, a sleep association, developmental disruption, or something else. Each has a different fix. This is where tracking becomes diagnostic rather than just informational — consistent patterns across multiple nights suggest habitual or association-driven waking, while variable patterns point to hunger or developmental disruption.
Finding 3: Babies “lose” about 3 hours of total sleep in the first year
Total average sleep drops from 15.24 hours at birth to 12.17 hours by 10 months — a reduction of roughly 3 hours. But this isn't sleep deprivation; it's developmental consolidation. The AAP (Paruthi et al., 2016) recommends 12–16 hours for infants 4–12 months, and our 10-month average of 12.17 hours is right at the lower end of that range.
Average total sleep by age (hours)
Where the sleep comes from shifts dramatically. Newborns average 3.2–3.6 naps per day. By 5–6 months that's down to 2.6–2.8. By 8–9 months, the 2-to-2 nap schedule is firmly in place at around 1.85 naps. And by 12–13 months, babies are transitioning toward a single nap (average 1.22–1.54 naps/day in our data, which aligns with the 12–15-month range most pediatric sleep researchers cite for the 2-to-1 transition).
What the data can't tell you — and what it can
Aggregate data tells you what's typical. But typical doesn't explain your baby. A 6-month-old waking 3 times per night is statistically normal. But is it happening because:
- The 6-month developmental leap is disrupting sleep architecture?
- A nursing-to-sleep association means every partial arousal triggers a full waking?
- The last nap is ending too late, compressing night sleep pressure?
- Teething is causing genuine discomfort at 2am?
These have completely different interventions. A sleep consultant would look at your specific log history and ask: is the wake window too long, or is there a sleep association at play? Is the bedtime drifting later this week compared to last?
This is exactly what Cocoo's AI sleep debugger does — it analyzes your logged data across multiple nights to flag whether the pattern looks like a developmental disruption, a timing issue, or a habitual wake. Instead of comparing your baby to an average, it compares tonight's pattern to your baby's baseline.
Why aggregate data isn't enough
Our dataset shows the 6-month sleep-through rate is 23.6%. But within that group, some babies are waking due to hunger (fixed by a dream feed or formula top-up), some due to a nursing association (fixed by a gradual pick-up-put-down approach), and some due to development (best addressed with good nap timing and wait-it-out). Knowing you're in a “normal” group doesn't tell you which fix applies to you.
How this compares to published research
Our findings align closely with several landmark sleep studies:
Galland et al. (2012) — systematic review of infant sleep norms
Found that night sleep hours increase from around 8.7h at 1 month to 10.4h at 6 months, stabilizing around 11h by 12 months. Our median data tracks closely: 9.47h at 1 month, 10.13h at 6 months, 10.96h at 12 months.
Henderson et al. (2010) — sleep consolidation over the first year
Found that the 6-month period is a critical transition point where many babies who had consolidated sleep regress. Our 23.6% sleep-through rate at 6 months (vs. 42.8% at 5 months) directly replicates this finding with real-world app data.
Jenni et al. (2005) — 4-month sleep architecture shift
Documented the transition from newborn-style sleep cycling to adult-like NREM/REM architecture around 3–4 months. Our 12-point drop in sleep-through rates from 3 to 4 months (44.5% → 32.4%) is a direct behavioral manifestation of this neurological event.
Mindell et al. (2016) — cross-cultural infant sleep norms
Large-scale study across multiple countries found night waking is highly prevalent in the first year and that the definition of “sleeping through the night” varies widely across cultures and clinicians. Our operational definition (zero logged wakings) is conservative; many studies use a 5- or 6-hour stretch as the benchmark.
What this means for your baby tonight
If your baby isn't sleeping through, the data tells you: you're not behind. The median baby in our dataset doesn't cross 60% sleep-through until 9 months. But “normal” doesn't mean inevitable — how your baby sleeps is largely shapeable by timing, environment, and sleep associations.
If you're in the 4-month dip
This is the hardest one to push through because the brain change is permanent. The fix is helping your baby fall asleep without a prop they'll miss at 2am — not eliminating comfort, just moving the comfort to earlier in the settling window. See our 4-month regression guide for specific steps.
If you're in the 6-month dip
This one hits hardest emotionally because you thought you were through it. Check: is the last nap ending within 2–2.5 hours of bedtime? Is there a clear nursing or rocking association at bedtime? The 6-month dip is often fixable with nap timing alone. Track for 5 days before making any changes — the pattern will usually tell you the cause.
If you're past 9 months and still waking 2+ times
By 9 months, the developmental disruptions have mostly passed. If your baby is still waking frequently, it's very likely a learned association rather than a developmental stage. This is the age where gentle sleep training is most effective — and most parents who track for a week before intervening find the pattern tells them exactly which wakes are habitual vs. genuine.
Frequently asked questions
When do babies actually sleep through the night?
Our data shows a true majority (60%+) first happens around 9 months. Before that, it's common but not typical — 44.5% at 3 months, dropping to 23.6% at 6 months. By 12 months, 87.5% of nights are wake-free.
Why is my baby suddenly waking more again?
The 4-month and 6-month disruptions are the two most predictable regression points, and both show clearly in our data. At 4 months, the brain permanently shifts to adult-like sleep cycling. At 6 months, developmental leaps and nap transitions cause a second dip. Neither is a sign of failure — they're developmental.
Is it normal for a 6-month-old to wake twice a night?
Yes — our data shows 6-month-olds average 1.40 wakings per night, and only 23.6% sleep through without any waking. Two wakings at 6 months is squarely within normal range. The more important question is whether those wakings are hunger, association, or developmental.
My baby was sleeping through but stopped — what changed?
Almost certainly a developmental milestone if it happened around 4 or 6 months. If it happened outside those windows, look first at sleep associations (did something change at bedtime?), then nap timing (did a nap drop or get too late?), then environment changes.
How much total sleep does a 6-month-old need?
Our data shows 6-month-olds averaging 12.31 total hours (night + naps). The AAP recommends 12–16 hours for 4–12-month-olds. An average of 10h night sleep + 2.5h in two naps = 12.5h, which is a healthy target for this age.
Want to understand how Cocoo uses this kind of data to diagnose your baby's specific sleep patterns? Learn about the research behind Cocoo's approach.
More from the Cocoo blog
Find out what's actually causing your baby's wake-ups
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Sources
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